NATURAL HISTORY, ECOLOGY, AND EVOLUTION OF A REMARKABLE ADAPTIVE RADIATION

Abstract

Review of: Losos, J. B. 2009. Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles. University of California Press, Berkeley, CA. ISBN: 9780520255913. Price. $75.00 What is an adaptive radiation? In its simplest form, it is the explosive diversification of a monophyletic lineage in response to the acquisition of a key innovation or colonization of new niches. What examples come to the mind of most students of evolutionary biology? Presumably, we all have our favorite example, but I would venture that most top five lists would include one or more of: Darwin’s finches on the Galapagos islands, African rift valley cichlids, Hawaiian honeycreepers, Hawaiian silverswords, and Greater Antillean Anolis lizards. These radiations are textbook classics because of the impressive diversity of form and function in their descendant lineages and/or because they have been studied thoroughly over relatively long periods of time. With the extremely well researched and entertainingly written Lizards in an Evolutionary Tree: Ecology and Adaptive Radiation of Anoles, Losos (2009) makes a rather convincing case that the latter group, along with their Lesser Antillean and mainland counterparts, may represent the ideal marriage of diversity to explore and study system tractability. To be fair, Losos does not directly make this bold claim; rather it is an impression one easily gets after reading the book. Chapter 1 begins with a brief introduction to the field of evolutionary biology, especially as it pertains to inferring historical events from fossil and phylogenetic evidence. In it, Losos makes a cogent defense of inferential approaches, aimed at those who take the narrow-minded view (again, these are my words here) that only experimental work constitutes (good) science. At the end of the chapter, Losos provides some insight into his introduction to the field and what motivates his continued interest in anoles. It is here that we first encounter a thread that will weave through the entire book, which is: although much is known about anoles, even more striking is how much remains undiscovered. Unlike some researchers who appear reluctant to bring other researchers into the fold (or, even, actively discourage others from working on “their” system), Losos (p. 10) extends an open invitation: “There’s plenty of room in the Anolis world for more researchers, and I will consider this book a success if it helps to produce a new generation of anole biologists.” Hear, hear! Throughout the book, Losos ends each chapter with a “Future Directions” section, sometimes brief, other times fairly substantial. Not wanting to steal his thunder, I largely do not touch on their contents, but I will say that they alone make this book a must read for new researchers in the field. With the scene set, the book really gets going in subsequent chapters. In Chapters 2–4 (the first of four informal sections), Losos introduces the diversity and distribution of anoles. Chapter 2 aims to define what anoles are, in terms of general phenotype, where they are found, and a short discussion of reproduction isolation and species concepts as they pertain to anole species. Having known the most about the ecomorphs (a term now widely used in ecology and evolution, it was first applied by the renowned Anolis biologist, Ernest Williams, in this context [see Footnote 72 in